A mangrove creek restoration plan utilizing hydraulic modeling

Abstract

Despite the valuable ecosystem services provided by mangrove ecosystems they remain threatened around the globe. Urban development has been a primary cause for mangrove destruction and deterioration in south Florida USA for the last several decades. As a result, the restoration of mangrove forests has become an important topic of research. Using field sampling and remote-sensing we assessed the past and present hydrologic conditions of a mangrove creek and its connected mangrove forest and brackish marsh systems located on the coast of Naples Bay in southwest Florida. We concluded that the hydrology of these connected systems had been significantly altered from its natural state due to urban development. We propose here a mangrove creek restoration plan that would extend the existing creek channel 1.1 km inland through the adjacent mangrove forest and up to an adjacent brackish marsh. We then tested the hydrologic implications using a hydraulic model of the mangrove creek calibrated with tidal data from Naples Bay and water levels measured within the creek. The calibrated model was then used to simulate the resulting hydrology of our proposed restoration plan. Simulation results showed that the proposed creek extension would restore a twice-daily flooding regime to a majority of the adjacent mangrove forest and that there would still be minimal tidal influence on the brackish marsh area, keeping its salinity at an acceptable level. This study demonstrates the utility of combining field data and hydraulic modeling to aid in the design of mangrove restoration plans.

Urbanization plays a minor role in the flooding and surface water chemistry of Puerto Rico’s mangroves

“…Yet the models presented in Figure 8 were no longer significant when MPNMAX was removed from the analysis, suggesting the site may be an unrepresentative outlier. Still, such a result would be expected from a decrease in tidal amplitudes in urban sites, which is consistent with indirect findings from another study (Marois and Mitsch 2017). Binomial comparisons of urban vs. non-urban corroborated this by showing lower average depths and flooding times, but longer hydroperiods in urban sites (Figure 8).…”

“…The influence of municipal sewage discharge on mangroves has been well documented and generally leads to nutrient enrichment, heavy metal contamination, and sometimes mortality (Clough et al 1983; Mandura 1997; Wong et al 1997; Branoff 2017). Further, a number of studies point to changes in mangrove coverage following large engineering projects that alter surrounding geomorphology, but these are not necessarily related to urbanization, or use qualitative or otherwise ambiguous definitions of “urban” (Colonnello and Medina 1998; Tian-Hong et al 2008; Sakho et al 2011; Marois and Mitsch 2017). Studies directly linking quantified variations in urbanization metrics, such as impervious surface coverage, population density, or forested area, with changes in mangrove flooding dynamics or surface water chemistry are absent from the literature.…”

Individual-based modeling of mangrove forest growth: MesoFON – Recent calibration and future direction

“…The impact of these hydro-geomorphological changes, such as coastal erosion, coastal recession and sinking deltas, might take decades to become apparent, but will be probably the most permanent ones (Wolanski and Elliott, 2015). Hydraulic models have been used to simulate the balance of freshwater and saltwater inflows in response to coastal engineering projects (Marois and Mitsch, 2017;Di Nitto et al, 2013), but certain ecosystem models have similar capabilities (compare ch. 4.1).…”

Determining hydrological flow paths to enhance restoration in impaired mangrove wetlands

“…Some proposed using hydraulic modeling to simulate flooding to perform hydrological and sedimentological restoration [32], while others considered the presence of mangrove species to classify the hydrological patterns and to make decisions on restoration actions [33]. Moreover, strategies aimed to improve mangrove recruitment have been applied.…”